diff --git a/lib/ash/actions/create.ex b/lib/ash/actions/create.ex
index b6877758..c758d2af 100644
--- a/lib/ash/actions/create.ex
+++ b/lib/ash/actions/create.ex
@@ -74,6 +74,7 @@ defmodule Ash.Actions.Create do
     |> validate_required_belongs_to()
     |> add_validations()
     |> require_values()
+    |> Ash.Changeset.cast_arguments(action)
   end
 
   defp require_values(changeset) do
diff --git a/lib/ash/actions/destroy.ex b/lib/ash/actions/destroy.ex
index 8799db90..99f53e00 100644
--- a/lib/ash/actions/destroy.ex
+++ b/lib/ash/actions/destroy.ex
@@ -30,7 +30,8 @@ defmodule Ash.Actions.Destroy do
 
     changeset = %{changeset | action_type: :destroy, api: api}
 
-    with :ok <- validate(changeset),
+    with %{valid?: true} <- Ash.Changeset.cast_arguments(changeset, action),
+         :ok <- validate(changeset),
          :ok <- validate_multitenancy(changeset) do
       destroy_request =
         Request.new(
diff --git a/lib/ash/actions/update.ex b/lib/ash/actions/update.ex
index 937d0505..17bad8ce 100644
--- a/lib/ash/actions/update.ex
+++ b/lib/ash/actions/update.ex
@@ -66,6 +66,7 @@ defmodule Ash.Actions.Update do
     |> Relationships.handle_relationship_changes()
     |> set_defaults()
     |> add_validations()
+    |> Ash.Changeset.cast_arguments(action)
   end
 
   defp run_action_changes(changeset, %{changes: changes}, actor) do
diff --git a/lib/ash/changeset/changeset.ex b/lib/ash/changeset/changeset.ex
index ec826868..a750efde 100644
--- a/lib/ash/changeset/changeset.ex
+++ b/lib/ash/changeset/changeset.ex
@@ -40,6 +40,7 @@ defmodule Ash.Changeset do
     :resource,
     :api,
     :tenant,
+    arguments: %{},
     context: %{},
     after_action: [],
     before_action: [],
@@ -75,10 +76,12 @@ defmodule Ash.Changeset do
   @type t :: %__MODULE__{}
 
   alias Ash.Error.{
+    Changes.InvalidArgument,
     Changes.InvalidAttribute,
     Changes.InvalidRelationship,
     Changes.NoSuchAttribute,
     Changes.NoSuchRelationship,
+    Changes.Required,
     Invalid.NoSuchResource
   }
 
@@ -203,6 +206,31 @@ defmodule Ash.Changeset do
     %{changeset | context: Map.merge(changeset.context, map)}
   end
 
+  @doc false
+  def cast_arguments(changeset, action) do
+    Enum.reduce(action.arguments, %{changeset | arguments: %{}}, fn argument, new_changeset ->
+      value = Map.get(changeset.arguments, argument.name)
+
+      if is_nil(value) && !argument.allow_nil? do
+        Ash.Changeset.add_error(
+          changeset,
+          Required.exception(field: argument.name, type: :argument)
+        )
+      else
+        with {:ok, casted} <- Ash.Type.cast_input(argument.type, value),
+             :ok <- Ash.Type.apply_constraints(argument.type, casted, argument.constraints) do
+          %{new_changeset | arguments: Map.put(new_changeset.arguments, argument.name, value)}
+        else
+          _ ->
+            Ash.Changeset.add_error(
+              changeset,
+              InvalidArgument.exception(field: argument.name)
+            )
+        end
+      end
+    end)
+  end
+
   @doc """
   Appends a record or a list of records to a relationship. Stacks with previous removals/additions.
 
@@ -486,6 +514,31 @@ defmodule Ash.Changeset do
     end
   end
 
+  @doc """
+  Add an argument to the changeset, which will be provided to the action
+  """
+  def set_argument(changeset, argument, value) do
+    %{changeset | arguments: Map.put(changeset.arguments, argument, value)}
+  end
+
+  @doc """
+  Remove an argument from the changeset
+  """
+  def delete_argument(changeset, argument_or_arguments) do
+    argument_or_arguments
+    |> List.wrap()
+    |> Enum.reduce(changeset, fn argument, changeset ->
+      %{changeset | arguments: Map.delete(changeset.arguments, argument)}
+    end)
+  end
+
+  @doc """
+  Merge a map of arguments to the arguments list
+  """
+  def set_arguments(changeset, map) do
+    %{changeset | arguments: Map.merge(changeset.arguments, map)}
+  end
+
   @doc """
   Force change an attribute if is not currently being changed, by calling the provided function
 
diff --git a/lib/ash/error/changes/invalid_argument.ex b/lib/ash/error/changes/invalid_argument.ex
new file mode 100644
index 00000000..c48fecba
--- /dev/null
+++ b/lib/ash/error/changes/invalid_argument.ex
@@ -0,0 +1,25 @@
+defmodule Ash.Error.Changes.InvalidArgument do
+  @moduledoc "Used when an invalid value is provided for an action argument"
+  use Ash.Error
+
+  def_ash_error([:field, :message], class: :invalid)
+
+  defimpl Ash.ErrorKind do
+    def id(_), do: Ecto.UUID.generate()
+
+    def code(_), do: "invalid_argument"
+
+    def message(error) do
+      "Invalid value provided#{for_field(error)}#{do_message(error)}"
+    end
+
+    defp for_field(%{field: field}) when not is_nil(field), do: " for #{field}"
+    defp for_field(_), do: ""
+
+    defp do_message(%{message: message}) when not is_nil(message) do
+      ": #{message}."
+    end
+
+    defp do_message(_), do: "."
+  end
+end
diff --git a/lib/ash/resource/actions/argument.ex b/lib/ash/resource/actions/argument.ex
new file mode 100644
index 00000000..1a18ed4e
--- /dev/null
+++ b/lib/ash/resource/actions/argument.ex
@@ -0,0 +1,27 @@
+defmodule Ash.Resource.Actions.Argument do
+  @moduledoc "Represents an argument to an action"
+  defstruct [:allow_nil?, :type, :name, constraints: []]
+
+  @type t :: %__MODULE__{}
+
+  def schema do
+    [
+      allow_nil?: [
+        type: :boolean,
+        default: true
+      ],
+      type: [
+        type: {:custom, Ash.OptionsHelpers, :ash_type, []},
+        required: true
+      ],
+      name: [
+        type: :atom,
+        required: true
+      ],
+      constraints: [
+        type: :keyword_list,
+        default: []
+      ]
+    ]
+  end
+end
diff --git a/lib/ash/resource/actions/create.ex b/lib/ash/resource/actions/create.ex
index a44993fb..1a4b59e6 100644
--- a/lib/ash/resource/actions/create.ex
+++ b/lib/ash/resource/actions/create.ex
@@ -1,11 +1,12 @@
 defmodule Ash.Resource.Actions.Create do
   @moduledoc "Represents a create action on a resource."
-  defstruct [:name, :primary?, :accept, :changes, :description, type: :create]
+  defstruct [:name, :primary?, :accept, :arguments, :changes, :description, type: :create]
 
   @type t :: %__MODULE__{
           type: :create,
           name: atom,
           accept: [atom],
+          arguments: [Ash.Resource.Actions.Argument.t()],
           primary?: boolean,
           description: String.t()
         }
diff --git a/lib/ash/resource/actions/destroy.ex b/lib/ash/resource/actions/destroy.ex
index f5a040be..ade48de8 100644
--- a/lib/ash/resource/actions/destroy.ex
+++ b/lib/ash/resource/actions/destroy.ex
@@ -1,11 +1,21 @@
 defmodule Ash.Resource.Actions.Destroy do
   @moduledoc "Represents a destroy action on a resource."
 
-  defstruct [:name, :primary?, :changes, :accept, :soft?, :description, type: :destroy]
+  defstruct [
+    :name,
+    :primary?,
+    :arguments,
+    :changes,
+    :accept,
+    :soft?,
+    :description,
+    type: :destroy
+  ]
 
   @type t :: %__MODULE__{
           type: :destroy,
           name: atom,
+          arguments: [Ash.Resource.Actions.Argument.t()],
           primary?: boolean,
           description: String.t()
         }
diff --git a/lib/ash/resource/actions/update.ex b/lib/ash/resource/actions/update.ex
index 671110f8..be7b62ec 100644
--- a/lib/ash/resource/actions/update.ex
+++ b/lib/ash/resource/actions/update.ex
@@ -1,12 +1,13 @@
 defmodule Ash.Resource.Actions.Update do
   @moduledoc "Represents a update action on a resource."
 
-  defstruct [:name, :primary?, :accept, :changes, :description, type: :update]
+  defstruct [:name, :primary?, :accept, :changes, :arguments, :description, type: :update]
 
   @type t :: %__MODULE__{
           type: :update,
           name: atom,
           accept: [atom],
+          arguments: [Ash.Resource.Actions.Argument.t()],
           primary?: boolean,
           description: String.t()
         }
diff --git a/lib/ash/resource/change/builtins.ex b/lib/ash/resource/change/builtins.ex
index bc6643e5..de21e6c9 100644
--- a/lib/ash/resource/change/builtins.ex
+++ b/lib/ash/resource/change/builtins.ex
@@ -19,4 +19,9 @@ defmodule Ash.Resource.Change.Builtins do
 
   @doc "A helper for builting filter templates"
   def actor(value), do: {:_actor, value}
+
+  @doc "A helper to confirm the value of one field against another field, or an argument"
+  def confirm(field, confirmation) do
+    {Ash.Resource.Change.Confirm, [field: field, confirmation: confirmation]}
+  end
 end
diff --git a/lib/ash/resource/change/confirm.ex b/lib/ash/resource/change/confirm.ex
new file mode 100644
index 00000000..708a0668
--- /dev/null
+++ b/lib/ash/resource/change/confirm.ex
@@ -0,0 +1,46 @@
+defmodule Ash.Resource.Change.Confirm do
+  @moduledoc false
+  use Ash.Resource.Change
+  alias Ash.Changeset
+  alias Ash.Error.Changes.InvalidAttribute
+
+  def init(opts) do
+    case opts[:field] do
+      nil ->
+        {:error, "Field is required"}
+
+      field when is_atom(field) ->
+        case opts[:confirmation] do
+          nil ->
+            {:error, "Confirmation is required"}
+
+          confirmation when is_atom(confirmation) ->
+            {:ok, [confirmation: confirmation, field: field]}
+
+          confirmation ->
+            {:error, "Expected an atom for confirmation, got: #{inspect(confirmation)}"}
+        end
+
+      field ->
+        {:error, "Expected an atom for field, got: #{inspect(field)}"}
+    end
+  end
+
+  def change(changeset, opts, _) do
+    confirmation_value =
+      Map.get(changeset.arguments, opts[:confirmation]) ||
+        Ash.Changeset.get_attribute(changeset, opts[:value])
+
+    if confirmation_value == Ash.Changeset.get_attribute(changeset, opts[:field]) do
+      changeset
+    else
+      Changeset.add_error(
+        changeset,
+        InvalidAttribute.exception(
+          field: opts[:field],
+          message: "Value did not match confirmation"
+        )
+      )
+    end
+  end
+end
diff --git a/lib/ash/resource/dsl.ex b/lib/ash/resource/dsl.ex
index cf6e30c3..cea0c605 100644
--- a/lib/ash/resource/dsl.ex
+++ b/lib/ash/resource/dsl.ex
@@ -229,6 +229,22 @@ defmodule Ash.Resource.Dsl do
     args: [:change]
   }
 
+  @action_argument %Ash.Dsl.Entity{
+    name: :argument,
+    describe: """
+    Declares an argument on the action
+
+    The type can be either a built in type (see `Ash.Type`) for more, or a module implementing
+    the `Ash.Type` behaviour.
+    """,
+    examples: [
+      "argument :password_confirmation, :string"
+    ],
+    target: Ash.Resource.Actions.Argument,
+    args: [:name, :type],
+    schema: Ash.Resource.Actions.Argument.schema()
+  }
+
   @create %Ash.Dsl.Entity{
     name: :create,
     describe: """
@@ -242,6 +258,9 @@ defmodule Ash.Resource.Dsl do
     entities: [
       changes: [
         @change
+      ],
+      arguments: [
+        @action_argument
       ]
     ],
     args: [:name]
@@ -275,6 +294,9 @@ defmodule Ash.Resource.Dsl do
     entities: [
       changes: [
         @change
+      ],
+      arguments: [
+        @action_argument
       ]
     ],
     target: Ash.Resource.Actions.Update,
@@ -293,6 +315,9 @@ defmodule Ash.Resource.Dsl do
     entities: [
       changes: [
         @change
+      ],
+      arguments: [
+        @action_argument
       ]
     ],
     target: Ash.Resource.Actions.Destroy,
diff --git a/lib/ash/type/type.ex b/lib/ash/type/type.ex
index 6399c0fd..a793b589 100644
--- a/lib/ash/type/type.ex
+++ b/lib/ash/type/type.ex
@@ -214,7 +214,7 @@ defmodule Ash.Type do
   Confirms if a casted value matches the provided constraints.
   """
   @spec apply_constraints(t(), term, constraints()) :: :ok | {:error, String.t()}
-  def apply_constraints({:array, type}, term, constraints) when is_list(constraints) do
+  def apply_constraints({:array, type}, term, constraints) when is_list(term) do
     list_constraint_errors = list_constraint_errors(term, constraints)
 
     case list_constraint_errors do
diff --git a/test/changeset/changeset_test.exs b/test/changeset/changeset_test.exs
index 5cba09f2..549226f4 100644
--- a/test/changeset/changeset_test.exs
+++ b/test/changeset/changeset_test.exs
@@ -15,7 +15,12 @@ defmodule Ash.Test.Changeset.ChangesetTest do
 
     actions do
       read :default
-      create :default
+      create :default, primary?: true
+
+      create :create_with_confirmation do
+        argument :confirm_name, :string
+        change confirm(:name, :confirm_name)
+      end
     end
 
     attributes do
@@ -739,4 +744,22 @@ defmodule Ash.Test.Changeset.ChangesetTest do
              } = changeset
     end
   end
+
+  describe "arguments" do
+    test "arguments can be used in valid changes" do
+      Category
+      |> Changeset.new(%{"name" => "foo"})
+      |> Changeset.set_argument(:confirm_name, "foo")
+      |> Api.create!(action: :create_with_confirmation)
+    end
+
+    test "arguments can be used in invalid changes" do
+      assert_raise Ash.Error.Invalid, ~r/Value did not match confirmation/, fn ->
+        Category
+        |> Changeset.new(%{"name" => "foo"})
+        |> Changeset.set_argument(:confirm_name, "bar")
+        |> Api.create!(action: :create_with_confirmation)
+      end
+    end
+  end
 end